The present invention is generally directed to toner processes, and more specifically, to chemical processes which involve the aggregation and fusion of latex, colorant, like pigment, or dye, and additive particles into toner particles, and wherein aggregation can be controlled by utilizing two coagulants, such as a polyaluminum chloride, preferably dissolved in an acid, like nitric acid, and an ionic surfactant such as Snail B, that is a benzylalkonium chloride, and wherein there is preferably selected a latex comprised of for example, submicron resin particles preferably in the size range of about 0.1 to about 0.4 micron in volume average diameter, suspended in an aqueous phase of water, nonionic and anionic surfactants to which is added a colorant dispersion comprising for example, preferably submicron colorant particles in the size range of 0.08 to 0.3 micron in volume average diameter, anionic surfactant, or optionally a nonionic surfactant, or mixtures thereof, and wherein the resultant blend is preferably stirred and heated to a temperature below about the resin Tg, resulting aggregates to which optionally is added a second latex, followed by adjusting the pH of the mixture with a base, and heating the mixture to a temperature above about the resin Tg to fuse the aggregates. The two coagulants selected appear to form a complex which results in neutralizing, or passivating the colorant.
More specifically, the present invention is generally directed to the aggregation and coalescence or fusion of latex, colorant, like pigment, dye, or mixtures thereof, in the presence of at least two coagulants, known initiators, and chain transfer agents, and wherein there is generated toner compositions with, for example, a volume average diameter of from about 1 micron to about 25 microns, and preferably from about 2 microns to about 10 microns, and a narrow particle size distribution of, for example, from about 1.10 to about 1.32, the size and size distribution being measured by a Coulter Counter, without the need to resort to conventional pulverization and classification methods, wherein a minimum amount of surfactant may be used, and wherein in embodiments washing of the toner permits the latex cleavable surfactant selected, which is hydrolyzable, or cleavable, to convert to a substantially inert form, or wherein the surfactant is converted to a form, which is easily removed from the toner, to provide a suitable toner triboelectrical charge, and wherein in this embodiment the removal of the surfactant selected is avoided and washing may not be needed, or wherein washing can be substantially reduced or eliminated. In important embodiments, the present invention relates to the use of cleavable nonionic surfactants, and which surfactants can be readily hydrolyzed by, for example, the addition of base to the surfactant in the pH range of from about 8 to about 13 into, or wherein the surfactants can be modified into water soluble components for simple washing thereof and removal from the toner generated. The toners generated can be selected for known electrophotographic imaging and printing processes, including digital color processes.
Toner generated by the processes of the present invention possess a number of advantages as compared to several emulsion/aggregation processes, these advantages including a coalescence time of about 0.5 to about 4 hours and a temperature in the range of 80 to about 90.degree. C. thereby permitting a process reduction time of about 40 to about 50 percent. Additionally, with the invention processes in embodiments toner washing can be reduced by about 60 to about 75 percent and the triboelectric charging values of the toner obtained are substantially constant irrespective of the colorant selected. Furthermore, when the toners generated are roll milled and aged over a period of for example, 2 hours there results stable and negative toner charging with for example, no wrong sign positively charged toner.
The toners generated with the processes of the present invention are especially useful for imaging processes, especially xerographic processes, which usually require high toner transfer efficiency, such as those with a compact machine design without a cleaner or those that are designed to provide high quality colored images with excellent image resolution, acceptable signal-to-noise ratio, and image uniformity.